Inappropriate antidiuretic hormone secretion in a neonate with meningitis

Hypotonic vs isotonic saline solutions for intravenous fluid management of acute infections

BACKGROUND

Hypotonic saline is commonly used as maintenance fluid in the management of acute infections. In recent years use of a hypotonic saline has been associated with adverse outcomes. To reduce the rates of adverse outcomes, use of isotonic saline as maintenance fluid has been suggested.

OBJECTIVES

To asses adverse events and benefits associated with infusion of hypotonic saline compared to isotonic saline solutions in the management of acute infections.

SEARCH STRATEGY

We searched MEDLINE, EMBASE, The Cochrane Controlled Trials Register, current controlled trials and the Specialised register of the Injuries Group.

SELECTION CRITERIA

Randomised trials comparing hypotonic saline to isotonic saline in the management of acute infections.

DATA COLLECTION AND ANALYSIS

Three reviewers independently evaluated all potentially relevant articles, examined each study for possible inclusion and assessed the methodology quality using the Cochrane guidelines.

MAIN RESULTS

No trials met our inclusion criteria.

REVIEWERS' CONCLUSIONS

We found no randomised controlled evidence to show that use of isotonic saline as a maintenance fluid instead of a hypotonic saline will lead to an improvement in outcomes. Randomised trials with adequate design and sample sizes are needed to evaluate the possible advantages and risks of using isotonic saline as maintenance fluid.

Bacterial meningitis: fluid balance and therapy

Fluid administration in children with meningitis should be conservative in an attempt to minimize cerebral edema and electrolyte disturbances that frequently complicate the course of meningitis. Since these complications have been shown to correlate with poor neurologic outcome, it is believed that appropriate fluid management will minimize the morbidity and mortality associated with bacterial meningitis in children.

Plasma and cerebrospinal fluid arginine vasopressin in patients with and without fever

Hyponatraemia has been described in association with a number of acute infectious diseases, mainly bacterial and tuberculous meningitis and pneumonia, and has been attributed to inappropriate secretion of arginine vasopressin (AVP). The mechanism of inappropriate AVP production is uncertain, but there is experimental evidence to suggest that fever may stimulate secretion of AVP into plasma and cerebrospinal fluid. In this study, AVP concentrations in plasma and cerebrospinal fluid from 37 febrile children with infections have been compared with those from 27 afebrile control subjects. Ten of the febrile children had meningitis (eight bacterial, two viral) and the remainder a variety of other infectious diseases. Seventy four per cent of febrile infected children were hyponatraemic (serum sodium less than 135 mmol/l) compared with only 8% of the afebrile controls. Plasma AVP concentrations were significantly higher in the febrile patients (median 2.92 pmol/l, range 1.0-23.25, n = 28) than in controls (median 1.67 pmol/l, range 0.57-6.0, n = 14) but there was no significant difference in cerebrospinal fluid AVP concentrations. There was no difference in plasma AVP concentrations between patients with meningitis and those with infections not involving the central nervous system. Careful attention should be paid to fluid and electrolyte balance in all children with acute infections.

Serial measurement of plasma arginine vasopressin in the newborn

Plasma arginine vasopressin was measured serially in 11 preterm infants and one asphyxiated, term infant. The samples were taken through umbilical arterial catheters placed at birth for blood gas measurements because ventilatory support was required. Plasma samples of 200 to 300 microliter were taken 4 to 12 hourly for up to 100 hours after birth. Plasma arginine vasopressin was measured by a cytochemical bioassay. A significant correlation between plasma arginine vasopressin and plasma osmolality was found in only two out of six infants. The normal 'resting' concentration was between 0.5 and 2 pg/ml. In five infants, apparent bursts of arginine vasopressin secretion were seen, and in one spontaneously breathing infant with respiratory distress, continuously high concentrations (12 to 25 pg/ml) were recorded over the first 100 hours.